Raised grain on stained oak after applying waterbase varnish - help!

We have stained some unfinished oak posts for a new railing with Saman brand water based wood stain - they looked great after this step. The we applied a 1 st coat of Samon brand waterbase varnish. The vanish has really raised the grain in the oak. It said to sand between coats of varnish& I thought this might help but it looks like the stain is being sanded off where the grain is raised so I quit sanding. Now what? Should I keep sanding, and will be able to restrain areas where stain is removed (there will still be varnish on many places) . Or do I apply another coat of varnish & will the raised fibres still sand out then? 0r is there something else I could do?

This is a great reason to not (post #207390, reply #5 of 6)

Having said that, if you would have wetted the wood with water it would have raised the grain prior to the stain, which can be sanded smooth once dry leaving a surface much less prone to raising with additional treatments of water-based stuff.